class_docstr: Selects features from a given stage.
code: def __init__(self, stage: str = "res5"):
      super().__init__()
      self.stage = stage
  
file_path: lightly/docs/source/tutorials_source/package/tutorial_pretrain_detectron2.py
imports: import torch
  from detectron2 import config, modeling
  from detectron2.checkpoint import DetectionCheckpointer
  from lightly.data import LightlyDataset
  from lightly.loss import NTXentLoss
  from lightly.models.modules import SimCLRProjectionHead
  from lightly.transforms import SimCLRTransform
label_desc: Use image node_id 1 to create a new SelectStage object from inherited base classes: torch.nn with example: obj = SelectStage(stage)